california, pennsylvania, west virginia. and there may be more cases as far away as france. >> this outbreak appears to be unusual in terms of the number of people affected and certainly the number of deaths we have seen. >>reporter: outbreak first traced to the popular curry village camp site where rodent had bury road into the insulation of tents. officials now believe a second camp site in the meadow also infected. last week warnings like these went out to continue,000 people who visited curry village since june. overnight notices went out to an additional 19,000 visitors. 29,000 recent park visit norse all. >> this is possibly the greatest cluster that has occurred certainly in the united states that i'm aware o of. >>reporter: early symptoms can take up to 6 weeks to the appear. include fatigue. fever and chills. those quickly give way to coughing and breathing problems as the lungs fill with fluid. the worst part is, there is no known treatment or cure. >> there's really nothing you can do preemptively if you were expo